| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Division of Respiratory Medicine, Department of Medicine, University of Cambridge School of Clinical Medicine, Addenbrooke's and Papworth Hospitals, Cambridge CB2 2QQ, United Kingdom
Submitted 4 August 2003 ; accepted in final form 27 March 2004
Long-term infusion of prostacyclin, or its analogs, is an effective treatment for severe pulmonary arterial hypertension. However, dose escalation is often required to maintain efficacy. The aim of this study was to investigate the mechanisms of prostacyclin receptor desensitization using the prostacyclin analog cicaprost in rat pulmonary artery smooth muscle cells (PASMCs). Desensitization of the cAMP response occurred in 63 nM cicaprost after a 6-h preincubation with agonist. This desensitization was reversed 12 h after agonist removal, and resensitization was inhibited by 10 µg/ml of cycloheximide. Desensitization was heterologous since desensitization to other Gs
-adenylyl cyclase (AC)-coupled agonists, isoproterenol (1 µM), adrenomedullin (100 nM), or bradykinin (1 µM), was also reduced by preincubation with cicaprost. The reduced cAMP response to prolonged cicaprost exposure appeared to be due to inhibition of AC activity since the responses to the directly acting AC agonist forskolin (3 µM) and the selective AC5 activator NKH-477 were similarly reduced. Expression of AC2 and AC5/6 protein levels transiently decreased after 1 h of cicaprost exposure. The PKA inhibitor H-89 (1 µM) added 1 h before cicaprost preincubation (6 h, 63 nM) completely reversed cicaprost-induced desensitization, whereas the PKC inhibitor bisindolylmaleimide (100 nM) was only partly effective. Desensitization was not prevented by the Gi inhibitor pertussis toxin. In conclusion, chronic treatment of PASMCs with cicaprost induced heterologous, reversible desensitization by inhibition of AC activity. Our data suggest that heterologous Gs desensitization by cicaprost is mediated predominantly by a PKA-inhibitable isoform of AC, most likely AC5/6.
prostacyclin; cyclic adenosine 5'-monophosphate; heterologous desensitization; cAMP-dependent protein kinase
This article has been cited by other articles:
|
|
 |
|
  H. El-Haroun, D. L. Clarke, K. Deacon, D. Bradbury, A. Clayton, A. Sutcliffe, and A. J. Knox IL-1{beta}, BK, and TGF-{beta}1 attenuate PGI2-mediated cAMP formation in human pulmonary artery smooth muscle cells by multiple mechanisms involving p38 MAP kinase and PKA Am J Physiol Lung Cell Mol Physiol, March 1, 2008; 294(3): L553 - L562. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Zhang, H. H. Patel, F. Murray, C. V. Remillard, C. Schach, P. A. Thistlethwaite, Paul. A. Insel, and J. X.-J. Yuan Pulmonary artery smooth muscle cells from normal subjects and IPAH patients show divergent cAMP-mediated effects on TRPC expression and capacitative Ca2+ entry Am J Physiol Lung Cell Mol Physiol, May 1, 2007; 292(5): L1202 - L1210. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. J. Wilson, J. K. Dowling, L. Zhao, E. Carnish, and E. M. Smyth Regulation of Thromboxane Receptor Trafficking Through the Prostacyclin Receptor in Vascular Smooth Muscle Cells: Role of Receptor Heterodimerization Arterioscler. Thromb. Vasc. Biol., February 1, 2007; 27(2): 290 - 296. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Matsumoto, K. Wakabayashi, T. Kobayashi, and K. Kamata Functional changes in adenylyl cyclases and associated decreases in relaxation responses in mesenteric arteries from diabetic rats Am J Physiol Heart Circ Physiol, November 1, 2005; 289(5): H2234 - H2243. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Nasrallah and R. L. Hebert Prostacyclin signaling in the kidney: implications for health and disease Am J Physiol Renal Physiol, August 1, 2005; 289(2): F235 - F246. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
